Stent and method of making same

ABSTRACT

A stent for vascular interventions having a hybrid open cell geometry. Variants of the stent include bare metal stents and drug-eluting stents. Embodiments of the stent include end projections for radiopaque markers or a discontinuous partial radiopaque coating on low-stress or low-strain regions of the peripheral stent. The stents of the invention are characterized by having thin walls, nested rows of struts, high expansion ratio, high and uniform radial force over entire diametric size and length of device, crush resistance up to and including about 90% of its fully expanded diameter, high fatigue resistance and high corrosion resistance.

BACKGROUND OF THE INVENTION

The present invention pertains generally to endoluminal stents used inminimally invasive procedures to restore and maintain patency ofanatomic passageways. More particularly, the present invention relatesto vascular stents capable of percutaneous delivery to blood vessels,including coronary, neurovascular and peripheral vessels requiringrestoration of blood flow and maintenance of vascular patency. Stillmore particular, the present invention pertains to a below-the-kneeintravascular stent characterized by having thin walls, nestedcircumferential rows of struts, high expansion ratio, high and uniformradial force over entire diametric size and length of device, crushresistance to at least 90% of its fully expanded diameter, high fatigueresistance and high corrosion resistance.

Stenting of peripheral blood vessels, particularly below-the-kneestenting, presents challenges that are not met by the current use ofcoronary stent designs applied in a peripheral intervention. Due toparticularly difficult device design and delivery requirements ofbelow-the-knee stenting, percutaneous transluminal angioplasty (PTA)also known as balloon angioplasty of the anterior or posterior tibialarteries or the peroneal artery is the current standard interventionprotocol for ischemic artery disease in this anatomical region. Thereis, however, substantial agreement that stand-alone balloon angioplastyof the below the knee arteries is sub-optimal because lesions in thisregion tend to be highly complex with risk factors including smallarterial diameter, lesion length, vascular dissections, diabetes and/orpoor arterial run off. It has been observed that after one year post-PTAfreedom from amputation, restenosis, or reintervention was only 18%.Feiring, A. J., “Below-the-Knee Drug-Eluting Stents,” Endovas. Today,August 2011, pp. 65-72. Feiring reviewed data supporting the overallefficacy of bare metal stents (BMS) and drug-eluting stents (DES) intreating below-the-knee chronic limb ischemia (CLI) and found that thebelow-the-knee DES registry data report 1,854 DES implanted in 765 limbswith CLI. There are an additional 517 patients who have been randomizedto balloon angioplasty or BMS versus DES. With the exception of a singlepaclitaxel DES study, all of the reported studies are concurrent intheir findings, reporting that DES for CLI is a safe and effectivetreatment that is superior to either balloon angioplasty or BMS.

Particular study findings included the ACHILLES trial which randomizedCLI patients to either the CYPHER DES (Cordis Corporation, Bridgewater,N.J.) or percutaneous transluminal angioplasty (PTA). The binaryrestenosis rates after 1 year were 19% with the CYPHER DES and 49% withangioplasty. The DESTINY trial randomized patients to the XIENCE DES(Abbott Vascular, Santa Clara, Calif.) versus the MULTILINK VISION BMS(Abbott Vascular). Primary patency rates at 1 year were 85% versus 54%,and target lesion revascularization was 9% versus 34% with DES versusBMS, respectively. The YUKON-BTK trial compared a proprietarynon-polymer sirolimus stent to the same uncoated BMS. The 1-year primarypatency rate for DES was 81% versus 56% for the BMS. Thus, after 1 year,all three randomized trials strongly endorsed the superiority of DESover balloon PTA or BMS.

While the data suggests that drug-eluting stenting of below-the-kneelesions is desirable, to date the commercially available drug-elutingstents have not achieved commercial success in the marketplace. TheCYPHER DES (Cordis Corporation) was discontinued in 2011 due to poorsales. The XIENCE PRIME DES (Abbott Vascular) is a coronary stent thatwas not approved by the U.S. Food and Drug Administration (USFDA) forbelow-the-knee indications. Similarly, the MULTI-LINK VISION BMS is acoronary stent which also has not been approved by the USFDA forbelow-the-knee indications.

Additionally, the ZILVER PTX DES (Cook Medical, Bloomington, Ind.) is acoronary stent design that has been approved by the USFDA forabove-the-knee femoropopliteal artery disease. Finally, the STENTYS BTK(Stentys, Paris, France) DES stent has been used in below-the-kneeinterventions and is the first BTK DES approved by the Notified Body forcommercial sale in Europe. The STENTYS BTK has not been approved by theUSFDA for below-the-knee interventions.

Each of these prior devices have been coronary stent designs that havebeen employed in peripheral, particularly, below-the-knee vascularinterventions. Heretofore, however, it has been unknown to design baremetal and/or drug-eluting stents to have properties that are optimallydesigned for delivery to and deployment within the below-the-kneevasculature.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a stentconfigured for delivery to and deployment within the peripheral,particularly below-the-knee, vasculature.

It is a further objective of the present invention to provide a baremetal stent configured for delivery to and deployment within theperipheral, particularly below-the-knee, vasculature.

It is another objective of the present invention to provide adrug-eluting stent configured for delivery to and deployment within theperipheral, particularly below-the-knee, vasculature.

It is yet another objective of the present invention to provide either abare metal stent or a drug-eluting stent for below-the-knee vascularinterventions which is characterized by having a high expansion ratio ofup to about 6.4:1.

It is a further objective of the present invention to provide a stentconfigured for peripheral below-the-knee vascular interventions in whichthe stent has a crimped delivery diameter down to about 0.84 mm for lowcrossing profile delivery and is compatible with a 3.5 French deliverysystem suitable for pedal access.

It is still another objective of the present invention to provide eithera bare metal stent or a drug-eluting stent for below-the knee vascularinterventions which is characterized by having a wall thickness betweenabout 50 to 100 μm.

It is yet still another objective of the present invention to provideeither a bare metal stent or a drug-eluting stent for below-the kneevascular interventions which is characterized by having a uniform radialstrength of at least 0.45 N/mm along its entire circumference andlength.

It is a further objective of the present invention to provide either abare metal stent or a drug-eluting stent for below-the knee vascularinterventions which is characterized by having a crush resistance to upto about 90% of the expanded diameter of the stent.

It is yet a further objective of the present invention to provide eithera bare metal stent or a drug-eluting stent for below-the knee vascularinterventions which is characterized by having at least 200% fatigueresistance, as determined by allowable alternating strain, when comparedto stents fabricated from wrought materials.

It is still yet a further objective of the present invention to provideeither a bare metal stent or a drug-eluting stent for below-the kneevascular interventions which is characterized by having lengths up toand including 200 mm.

It is another objective of the present invention to provide a stent forbelow-the knee vascular interventions which is characterized by having amicro-textured outer surface configured for drug-loading.

It is still another objective of the present invention to provide abelow-the-knee vascular stent having volume-enhancing features in or onthe outer surface of the stent and a drug eluting coating on the outersurface and within the volume-enhancing features.

It is a further objective of the present invention to provide aperipheral vascular stent in which the volume-enhancing features in oron the outer surface of the stent increases the surface volume of thestent relative to a stent of like dimensions that does not have thevolume-enhancing features.

It is yet another objective of the present invention to provide abelow-the-knee vascular stent having volume-enhancing features in or onthe outer surface having a depth between about 2 μm to about 25 μm and aspacing between adjacent volume-enhancing features of about 2 μm toabout 25 μm.

It is still a further objective of the present invention to provide abelow-the-knee vascular stent having a varied thickness profile of adrug-eluting coating that regulates the drug-elution profile when thestent is implanted into a blood vessel.

It is still another objective of the present invention to provide abelow-the-knee vascular stent having a plurality of circumferential ringstructures interconnected by a plurality of bridge members defining aplurality of open cells.

It is another further objective of the present invention to provide abelow-the-knee vascular stent having a first set of open cells atproximal and distal ends of the stent and a second set of open cells,having a different geometry than the first set of open cells, along anintermediate section of the stent between the proximal and distal endsof the stent.

It is yet another objective of the present invention to provide abelow-the-knee vascular stent having a layer of radiopaque material onat least a portion of the outer surface of the stent.

It is still another objective of the present invention to provide abelow-the-knee vascular stent in which a layer of radiopaque material isselectively provided on low-stress portions of the stent.

It is still yet another objective of the present invention to provide abelow-the-knee vascular stent having a plurality of projectionsextending from opposing proximal and distal ends of the stent, each ofthe plurality of projections being configured to couple to a radiopaquemarker.

It is a further objective of the present invention to provide abelow-the-knee vascular stent having a plurality of projectionsconfigured as open frame members each having outer structural membersdefining a central open region bounded by the outer structural membersand a radiopaque cuff coupled to the open frame members andsubstantially occupying the central open region of the projections.

These and other objects, features and advantages of the presentinvention will be more apparent to those skilled in the art from thefollowing more detailed description of the present invention taken withreference to the accompanying drawings. The above summary is notintended to describe each disclosed embodiment or every implementationof the present invention. The Figures and Detailed Description thatfollow more particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is side elevational view of a stent in accordance with a firstembodiment of the present invention.

FIG. 2 is a flat view of the stent in accordance with the firstembodiment of the present invention.

FIG. 3 is a flat view of a stent in accordance with a second embodimentof the present invention.

FIG. 4 is a fragmentary plan view of the stent in accordance with thefirst and second embodiments of the present invention.

FIG. 5 is a side elevational view of a portion of a prior art coronarystent employed in peripheral below-the-knee interventions.

FIG. 6 is a side elevational view of a portion of the inventive stent inaccordance with the second embodiment of the present invention.

FIG. 7 is a perspective view of a terminal end portion of an inventivestent in accordance with a third embodiment of the present invention.

FIG. 8A is a cross-sectional view taken along line 8A-8A of FIG. 7.

FIG. 8B is a fragmentary view of a section of FIG. 8A.

FIG. 9 is a diagrammatic cross-sectional view of a fourth embodiment ofthe inventive stent.

FIG. 10 is a diagrammatic cross-sectional view of a fifth embodiment ofthe inventive stent.

FIG. 11 is a fragmentary perspective of a terminal end portion of thestent in accordance with the first embodiment of the present invention.

FIG. 12 is a fragmentary side elevational view of the end portion of thestent in accordance with the first embodiment of the present invention.

FIG. 13 is a fragmentary plan view of the end portion of the inventivestent illustrating a radiopaque marker affixed to the end portion inaccordance with the first embodiment of the present invention.

FIG. 14 is a fragmentary side elevational view of the end portion of thestent illustrating a radiopaque marker affixed to the end portion inaccordance with the first embodiment of the present invention.

FIG. 15A is a side elevational view of a portion of the stent inaccordance with a sixth embodiment of the present invention.

FIG. 15B is a cross-sectional view taken along line 15B-15B of FIG. 15A.

FIG. 15C is a cross-sectional view taken along line 15C-15C of FIG. 15A.

FIG. 16 is a perspective view of a system for forming a radiopaque layeron the inventive stent in accordance with a sixth embodiment of themethod of the present invention.

FIG. 17 is a perspective view of a system for forming a radiopaque layeron the inventive stent in accordance with a sixth embodiment of themethod of the present invention.

FIG. 18 is perspective view of a delivery system for the inventiveembodiments of the inventive stent.

FIG. 19 is a fragmentary side elevational view of a delivery systemhandle in accordance with the present invention.

FIG. 20A is a fragmentary side elevational view of the delivery systemhandle in accordance with the present invention illustrating the handlewhere the stent is in an un-deployed state.

FIG. 20B is a fragmentary side elevational view of the delivery systemhandle in accordance with the present invention illustrating the handlewhere the stent is in a deployed state.

FIG. 21 is a radial force curve vs. expansion diameter for an exemplary5.2 mm×30 mm stent in accordance with the present invention.

FIG. 22 is a radial force curve vs. expansion diameter for an exemplary3.8 mm×30 mm stent in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The device, system and methods of the present invention will bedescribed with reference to certain exemplary embodiments thereof. Theseexemplary embodiments are intended to be illustrative and non-limitingexamples of the present invention. The example embodiments are providedso that this disclosure will be thorough, and will fully convey thescope to those who are skilled in the art. Numerous specific details areset forth such as examples of specific components, devices, and methods,to provide a thorough understanding of embodiments of the presentdisclosure. It will be apparent to those skilled in the art thatspecific details need not be employed, that example embodiments may beembodied in many different forms and that neither should be construed tolimit the scope of the disclosure. Those of ordinary skill in the artwill understand and appreciate that variations in materials, structure,material properties, and tolerances may be made without departing fromthe scope of the invention, which is defined only by the claims appendedhereto and their range of equivalents. In some example embodiments,well-known processes, well-known device structures, and well-knowntechnologies are not described in detail.

For ease of understanding, the present invention is described withreference to the accompanying Figures. In the accompanying Figures likeelements are identified by like reference numerals.

For purposes of clarity, the following terms used in this patentapplication will have the following meanings:

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “an,” and “the” may be intended to includethe plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

“Substantially” is intended to mean a quantity, property, or value thatis present to a great or significant extent and less than totally.

“About” is intended to mean a quantity, property, or value that ispresent at ±10%. Throughout this disclosure, the numerical valuesrepresent approximate measures or limits to ranges to encompass minordeviations from the given values and embodiments having about the valuementioned as well as those having exactly the value mentioned. Otherthan in the working examples provided at the end of the detaileddescription, all numerical values of parameters (e.g., of quantities orconditions) in this specification, including the appended claims, are tobe understood as being modified in all instances by the term “about”whether or not “about” actually appears before the numerical value.“About” indicates that the stated numerical value allows some slightimprecision (with some approach to exactness in the value; approximatelyor reasonably close to the value; nearly). If the imprecision providedby “about” is not otherwise understood in the art with this ordinarymeaning, then “about” as used herein indicates at least variations thatmay arise from ordinary methods of measuring and using such parameters.In addition, disclosure of ranges includes disclosure of all values andfurther divided ranges within the entire range, including endpointsgiven for the ranges.

“Shape memory alloy” is intended to mean a binary, ternary, quaternarymetal alloy that recover apparent permanent strains when raised above anAustenitic transformation temperature (A_(s)). Shape memory alloys havetwo stable phases, i.e., a high-temperature or Austenite phase and alow-temperature or Martensite phase.

“Superelastic” is intended to mean a property of a materialcharacterized by having a reversible elastic response in response to anapplied stress. Superelastic materials exhibit a phase transformationbetween the austenitic and martensitic phases as the applied stress isloaded or unloaded.

“Radiopaque” is intended to mean any material that obstructs passage ofradiation and increases contrast to X-ray or similar radiation imaging.

“Sinusoidal” is intended to mean a structure having a wave-form patterncharacterized by sine and cosine functions as well as a wave-formpattern that is not rigorously characterized by those functions butnevertheless resemble such in a more general way. As a general example,a waveform pattern includes those characterized as having one or morepeaks and valleys that are generally U-shaped, bulbous, or are moretriangular in shape, such as V-shaped, zig-zag, or saw-tooth shaped, orwhose peaks and valleys are generally square or rectangular.

The terms “peak” and “valley” shall be defined with respect to theproximal and distal opposing ends of the stent. Moreover, for the sakeof clarity, the terms “peak” and “valley” in reference tocircumferential ring member or sub-element thereof are intended toinclude not only the point(s) of maximum or minimum amplitude on acircumferential ring, but also a small region around the maximum orminimum. More precisely, in the case of peaks, the ‘small region’ aroundthe maximum is intended to include any point along the ring member whichis distal of a line extending through the innermost part of the ringmember at the maximum amplitude and perpendicular to the longitudinalaxis of the stent up to the peak itself. In the case of valleys, the‘small region’ around the minimum is intended to include any point alongthe ring member which is proximal of a line extending through theinnermost part of the ring member at the minimum amplitude andperpendicular to the longitudinal axis of the stent up to the valleyitself.

The term “volume-enhancing feature” is intended to mean a topographicalfeature on or in an abluminal (outer) or luminal (inner) surface of astent that increases the surface area or surface volume of the stentwhen compared to a stent surface without the volume-enhancing feature.Examples of such topographical volume-enhancing features include,without limitation, surface depressions such as grooves or trenches andsurface protrusions such as pyramidal, conical, columnar, cylindrical,cubic or other polygonal projections. Surface volume may be determinedby conventional measurement methods, such as, for example, ISO 4287:1997or ASTM D4417. For purposes of this application, the term “groove” or“grooves” is used for ease of reference and illustration and as anexample of a volume-enhancing feature. The terms “groove” and“volume-enhancing feature” are used interchangeably in this description.

Several alternative variants of the present invention are illustrated inthe accompanying Figures. The embodiments of the peripheralbelow-the-knee stent are characterized by a tubular stent having aplurality of generally sinusoidal circumferential ring members withadjacent ring members being interconnected by at least one bridge memberextending between a peak of a first ring member and a peak of anadjacent ring member and at least one bridge member extending between avalley of a first ring member and a valley of an adjacent ring member.The peak-peak bridge members alternate with the valley-valley bridgemembers along successive circumferential rows along a longitudinal axisof the tubular stent. The ring members each have a plurality ofsubstantially linear strut members with opposing ends of each of thesubstantially linear strut members begin contiguous with one of a peakor a valley of the circumferential ring member.

The alternative variants differ from each other in one or more of thefollowing general aspects: 1) configuration of the radiopaque markers;2) surface topography the outer surface of the stent; and/or 3) presenceor absence of a drug coating on the outer surface of the stent. Theembodiments of the peripheral below-the-knee stent of the presentinvention include the following:

-   -   i. stent having proximal and distal projections and radiopaque        materials coupled to the proximal and distal projections;    -   ii. stent having proximal and distal projections, radiopaque        materials coupled to the projections, and volume-enhancing        features on an outer or abluminal surface of the stent;    -   iii. stent having proximal and distal projections, radiopaque        materials coupled to the projections, volume-enhancing features        on the abluminal surface of the stent, and a drug coating on the        abluminal stent surface and in the volume-enhancing features;    -   iv. stent having no proximal and distal projections and        radiopaque materials coating only low-stress regions of the        abluminal surface of the stent;    -   v. stent having no proximal and distal projections,        volume-enhancing features on the abluminal surface of the stent,        and radiopaque materials coating low-stress regions of the        abluminal surface of the stent and in the volume-enhancing        features;    -   vi. stent having no proximal and distal projections, radiopaque        materials coating low-stress regions of the abluminal surface of        the stent, and volume-enhancing features in the radiopaque        material on the abluminal surface of the stent;    -   vii. stent having no proximal and distal projections,        volume-enhancing features on the abluminal surface of the stent,        radiopaque materials coating low-stress regions of the abluminal        surface of the stent, and a drug coating over the radiopaque        materials coating, the abluminal surface of the stent and in the        volume-enhancing features; and/or    -   viii. stent having no proximal and distal projections,        radiopaque materials coating low-stress regions of the abluminal        surface of the stent, volume-enhancing features in the        radiopaque material on the abluminal surface of the stent, and a        drug coating over the radiopaque materials coating, over the        abluminal surface of the stent and in the volume-enhancing        features.

In a first embodiment of the invention, the stent includes a pluralityof projections at each of the proximal and distal end of the stent. Eachof the projections is contiguous with a peak of a terminalcircumferential ring of the stent. Each of the projections comprises aframe defining a central open region. A radiopaque cuff is joined toeach of the plurality of projections and covers the central open region.The radiopaque cuff preferably wraps around and is secured to the frameof each projection.

In a second embodiment of the invention, the stent does not include aplurality of projections at each of the proximal and distal ends of thestent. Rather in the second embodiment, a radiopaque layer is coatedonto an outer surface of the stent only at low-stress regions of thestent. The low-stress regions of the stent are typically the strutregions of the stent between the peaks and the valleys and not on thepeaks and valleys or on the bridge members.

In a third embodiment of the invention, the stent has a drug-elutingcoating on the outer surface of the stent, with the stent being eitherthe first embodiment or the second embodiment described above.

In a fourth embodiment of the invention, either the first or secondembodiments of the stent, as described above, may be employed. Aplurality of surface volume-enhancing features, such as, for example,elongate grooves, are formed in or on the outer surface of the stentabout at least a substantial extent of the stent's entire length. Theplurality of volume-enhancing features are preferably oriented generallyparallel to the longitudinal axis of the stent when the stent is in itsdiametrically expanded state. The plurality of volume-enhancing featuresmay, optionally, also be formed in the plurality of projections andradiopaque cuff in accordance with the first embodiment of theinvention. Optionally, the plurality of volume-enhancing features may beformed in the outer surface of the stent prior to coating the stent withthe radiopaque material in accordance with the second embodiment of theinvention described above.

In a fifth embodiment of the invention, the third and fourth embodimentsare combined such that the stent has a plurality of volume-enhancingfeatures in or on either the outer surface of the stent or in the outersurface of the radiopaque coating and has a drug-eluting coating on theouter surface of the stent and/or the outer surface of the radiopaquecoating. At least a portion of the drug elution coating is disposedwithin the volume-enhancing features. Those skilled in the art willappreciate that the volume-enhancing features or grooves provideadditional surface volume to the stent and, therefore, accommodates agreater volume of the drug-eluting coating and, hence, a greaterquantity of the drug than would be present with a drug-eluting coatingwhen compared to a stent having a non-grooved surface.

In a sixth embodiment of the invention, the stent in accordance with anyof the first, second, third, fourth and fifth embodiments is provided,with the stent having a hybrid structure of open cells, with a firstopen cell geometry positioned at proximal and distal ends or regions ofthe stent and a second open cell geometry begin present at anintermediate region of the stent.

In a seventh embodiment of the invention, a planar mask having anelongate opening is provided for coating the outer surface of a stentwith a radiopaque material.

In an eighth embodiment of the invention, a cylindrical mask having aplurality of elongate openings is provided for coating the outer surfaceof a stent with a radiopaque material.

In a ninth embodiment of the invention, a stent delivery system isprovided. The delivery system comprises, generally, a catheter ontowhich the inventive sent is mounted toward a distal end of the catheter,an atraumatic tip at the distal end of the catheter, a sheathconcentrically engaged about the catheter and configured to enclose thestent between the catheter and the sheath during delivery, a handlecoupled to both the catheter and the sheath and having a retractionmechanism operably coupled to the sheath. Actuation of the retractionmechanism, retracts the sheath proximally into the handle, therebyexposing the stent for delivery to a desired site within a body.

The foregoing general descriptions of the variants of the invention willbe described in greater particularity with reference to the accompanyingFigures.

Turning to FIGS. 1 and 2, the inventive peripheral below-the-knee stent10 is shown. In accordance with the first embodiment of the invention,stent 10 is a tubular member having a first end 12 and a second end 14corresponding to the proximal and distal ends of the stent. Stent 10also has a longitudinal axis L and a circumferential axis C. Stent 10 iscomposed of a plurality of rings 16 extending about the circumferentialaxis C of stent 10. Laterally adjacent pairs of rings 16 areinterconnected by at least one of a plurality of bridge members 18. Eachof the rings 16 has a sinusoidal configuration with a plurality of peaks32 and valleys 40. One of the plurality of bridge members 18interconnects a peak 40 of one ring 16 to a valley 32 of a secondadjacent ring 16. More than one bridge member 18 preferablyinterconnects adjacent rings 16 about their circumference. The bridgemembers 18 support adjacent rings 16 in a spaced apart relationship anddefine a plurality of cells 24, 28 in the space bounded by the bridgemembers 18 and sections of the rings 16.

In each of the embodiments of the stent of the present invention, eachof the plurality of bridge members 18 are substantially linear and,optionally, may have a taper in either width and/or thickness at an endof the bridge member 18 that connects to a valley 32. This taper willaid in bend flexibility of the stent 10.

The cells 24, 28 are preferably a hybrid of different open cellgeometries. As is known in the stent arts, closed-cells arecharacterized by small free cell areas between struts and bridge membersand are constrained from longitudinal flexion about their entire freecell area. In contrast, open-cells have relatively larger free cellareas between struts or bridge members and have unconstrained regions ofthe free cell area. For purposes of the present application, referenceto cell shape or cell area will be made based upon their shape or areawhen the stent is in its diametrically expanded state. Cells 24, 28 areopen regions defined between longitudinally adjacent rings 16 andextending about the circumferential axis of the stent 10. The bridgemembers 18 delimit circumferentially adjacent cells 24, 28.

In accordance with the first embodiment of stent 10, as depicted inFIGS. 1 and 2, or in accordance with the second embodiment of stent 30,depicted in FIG. 3, and in the enlarged view of FIG. 4, first cell 24 isan open cell having a substantially V-shape and second cell 28 is anopen cell having a generally Z-shape. The substantially V-shaped firstcells 24 are positioned at each of the proximal end 12 and the distalend 14 of the stent 10, 30, while the substantially Z-shaped secondcells 28 are positioned along an intermediate region 26 of stent 10, 30.This arrangement of open cells 24, 28 lends high degrees of longitudinalflexibility and radial expandability to the stent 10, 30.

The stents 10, 30 of the present invention have a wall thickness betweenabout 50 μm and about 100 μm, with the wall thickness preferably betweenabout 75 μm to about 95 μm. The wall thickness is ideally generallyuniform about the longitudinal axis and circumferential axis of thestent 10, 30. The stents 10, 30 have an expansion ratio of up to about6.4:1 and are capable of being crimped to an outer diameter of about0.84 mm outer diameter and radially expand up to an outer diameter ofabout 5.4 mm. The crimped diameter of about 0.84 mm allows for use of a3.5 French delivery catheter sheath, which is well suited topercutaneous delivery through pedal access. Those skilled in the artwill understand that the foregoing dimensions, ratios, sizes and othervalues are exemplary and that other wall thicknesses, expansion ratios,crimp diameters, expansion diameters, delivery sheath sizes and the likeare also intended by the present invention.

Stents 20, 30 are preferably made of shape memory alloy and/orsuperelastic alloy. As noted above, shape memory and/or superelasticalloys may be binary, ternary, quaternary, quinary or n-ary, where n- isan integer of the base value metal alloys. While binary nickel-titaniumalloys are well known in the art, other alloy additions of platinum,palladium, tantalum, tungsten, zirconium, hafnium and/or gold may alsobe used. Further, it is preferably that the stents 20, 30 be made byphysical vapor deposition of shape memory alloy and/or superelasticalloy materials onto a cylindrical mandrel to form a stent hypotube onthe cylindrical mandrel. The stent 20, 30 pattern geometry thenpreferably laser cut into the stent hypotube and then removed from thecylindrical mandrel.

Physical vapor deposition of shape memory alloys and/or superelasticalloys onto cylindrical mandrels is known in the art. Such processes areexemplified by U.S. Pat. Nos. 6,379,383, 7,335,426, 9,640,359, each ofwhich are hereby incorporated by reference.

The second embodiment of the stent 30 is illustrated with reference toFIG. 3. Stent 30 has the same structure of rings 16 and bridge members18, but lacks the proximal and distal projections 20 or radiopaque cuffs22 coupled to the proximal and distal projections 20. Instead of theproximal and distal projections 20 and radiopaque cuffs, stent 30 has acoating of radiopaque material on portions of the outer or abluminalsurface of the stent 30 as will be described in greater detail withreference to FIG. 9 hereinafter. Like stent 10, stent 30 is made of ashape memory or superelastic material.

As best seen in FIG. 4, each peak 40 has an innermost part 56 and anoutermost part 57 of the peak 40. The innermost part 56 of peak 40 lieson a lateral surface of the ring member 16 and is positioned in theincluded angle formed by the adjacent struts 36 of which the peak 40 isthe vertex. The outermost part 57 of peak 40 lies on an opposing lateralsurface of the ring member 16 as the innermost part 56 and is positionedat the vertex of peak 40. Similarly, an innermost part 54 of valley 32lies on a lateral surface of the ring member and is positioned in theincluded angle formed by the adjacent struts 36 of the valley 32. Anoutermost part 52 of valley 32 lies on an opposing lateral surface ofthe ring member as the innermost part 54 and is positioned at the vertexof the valley 32.

Again, as best illustrated in FIGS. 2 and 4, each ring 16 is comprisedof generally linear strut members 36 that extend in a generally helicalaxis, with either a right-handed or a left-handed orientation relativeto the longitudinal axis L, of the stent 10, 30 and between a peak 40and a valley 32 on each of the plurality of rings 16. In this manner,the sinusoidal shape of each ring 16 is formed. Optionally, the strutmembers 36 may be provided with an offset section 38, as bestillustrated in FIG. 4, present at an intermediate point along a lengthof the strut members 36. The offset section 38 is preferably a lateraloffset along the circumferential axis of the stent 10. Offset section 38allows adjacent rings 16 to nest relative to each other and assists inallowing for the very low crimped profile and low crossing profile ofthe stent embodiments during delivery.

A first set of bridge members 18 a interconnect an outermost portion 52of a valley 32 with an innermost portion 54 of a valley 32 on anadjacent ring 16, while a second set of bridge members 18 b interconnectan innermost portion 56 of a peak 40 with an outermost portion 58 of anadjacent ring 16. Optionally, and preferably, the bridge members of thefirst set of bridge members 18 a are in alignment with along thelongitudinal axis of the stent 10, 30 while the bridge members of thesecond set of bridge members 18 b are in alignment with the longitudinalaxis of the stent 10, 30.

As noted above, adjacent rings 16 are maintained in spaced apartrelationship by bridge members 18. Adjacent rings 16 are insubstantially synchronous alignment such that the peaks 40 and valleys32 of adjacent pairs of rings 16 are in substantial alignment about boththe circumferential axis C and longitudinal axis L of stent 10, 30. Inthis manner, a plurality of rows 11 are formed between adjacent rings 16along the longitudinal axis of the stent 10, 30. As best illustratedwith reference to FIG. 4, the plurality of rows 11 are denoted as rows11 a, 11 b, 11 c, 11 d, 11 e and 11 f. While only a few rows areillustrated in the enlarged fragmentary view of FIG. 4, those skilled inthe art will appreciate, as illustrated in FIGS. 1-3, that the pluralityof rows 11 extend along the entire longitudinal axis of the stent 10, 30ending only with the terminal rings 16 at the first end 12 and secondend 14 of the stent 10, 30.

Rows 11 are the circumferential spaces between longitudinally adjacentrings 16 and include the bridge members 18 that maintain spacing betweenthe longitudinally adjacent rings 16 forming each row 11. The first setof bridge members 18 a and the second set of bridge members 18 b are incircumferentially spaced apart relationship relative to one another andstaggered in alternating rows 11. This staggered relationship of thefirst set of bridge members 18 a and the second set of bridge members 18b is illustrated in FIG. 4 wherein the first set of bridge members 18 aare in row 11 a and the second set of bridge members 18 b are in row 11b and are circumferentially offset from the first set of bridge members18 a. The first set of bridge members 18 a are generally aligned alongthe longitudinal axis L of the stent 10, 30 and staggered in alternatingrows 11. As illustrated in FIG. 4, first set of bridge members 18 a arefound in rows 11 a, 11 c and 11 e. Similarly, the second set of bridgemembers 18 b are generally aligned along the longitudinal axis L of thestent 10, 30 and are staggered in alternating rows 11. Also asillustrated in FIG. 4, second set of bridge members 18 b are found inrows 11 b, 11 d and 11 f. These staggered patterns of bridge members 18along the longitudinal axis L and offset patterns of bridge members 18about the circumferential axis C of stent 10, 30 are repeated along theentire intermediate section 26 of stent 10, 30.

In accordance with all embodiments of the stent 10, 30 of the presentinvention, the terminal end rows 11 at each of the first end 12 and thesecond end 14 of the stent 10, 30 are optionally configured as acircumferential series of V-shaped first open cells 24. As illustratedin FIGS. 2, 3 and 5, the V-shaped open cells 24 are formed by adjacentrings 16 synchronously positioned with peak 40 to peak 40 and valley 32to valley 32 alignment in the longitudinal axis L of the stent 10, 30.Bridge members 18 interconnect adjacent peaks 32 and adjacent valleys 40in the adjacent rings 16.

The above-described hybrid combination of first open cells 24 and secondopen cells 28 having different open cell geometries, in combination withthe shape memory or superelastic alloy construction of stent 10, 30,lends both column and radial strength and longitudinal flexibility tothe stent 10, 30. These attributes are crucial to achieve high expansionratios of up to or greater than 6:1, crush resistance to at least about90% of the expanded diameter of the stent, a stent having a crimpdiameter down to about 0.85 mm for low-crossing profile deliverycompatible with a 3.5 French delivery system suitable for pedal access,and a uniform radial strength of at least about 0.5 N/mm along thestent's entire circumference and length. These features of the stent 10,30 are all present where the stent 10, 30 has a wall thickness betweenabout 50 to about 100 μm, more particularly between about 60 μm to about90 μm and even more particularly between about 75 μm and about 95 μm,and stent 10, 30 lengths up to about 200 mm.

Physical vapor deposition of the shape memory or superelastic alloy ofthe stent 10, 30 creates a stent material that is characterized byhaving at least 200% fatigue resistance and higher corrosion resistancewhen compared with stents fabricated from the same shape memory orsuperelastic materials made by wrought material processing, whichrequire secondary passivation to achieve acceptable fatigue andcorrosion resistance.

One of ordinary skill in the art is able to readily derive and comparecorrosion resistance and fatigue resistance of both the inventive stentand stents made from wrought materials without the exercise of routineexperimentation. Ample guidance is available to measure corrosion andfatigue resistance, as well as axial and radial strength and crushresistance with reference to both regulatory guidance and standard testmethodologies. For example, corrosion resistance for stents may bedetermined by ASTM F2129-17b, Standard Test Method for Conducting CyclicPotentiodynamic Polarization Measurements to Determine the CorrosionSusceptibility of Small implant Devices, ASTM international, WestConshohocken, Pa., 2017, www.astm.org. Fatigue resistance for stents maybe determined by ASTM F2477-07(2013), Standard Test Methods for in vitroPulsatile Durability Testing of Vascular Stents, ASTM International,West Conshohocken, Pa., 2013, www.astm.org and/or ASTM F2942-13,Standard Guide for in vitro Axial, Bending, and Torsional DurabilityTesting of Vascular Stents. ASTM International, West Conshohocken, Pa.,2013, www.astm.org. The United States Food and Drug Administration hasalso issued a Guidance for Industry and FDA Staff entitled Non-ClinicalEngineering Tests and Recommended Labeling for Intravascular Stents andAssociated Delivery Systems (Apr. 18, 2010) and Select Updates forNon-Clinical Engineering Tests and Recommended Labeling forIntravascular Stents and Associated Delivery Systems (Aug. 18, 2015)both of which provide guidance on corrosion and fatigue testing forstents and are hereby incorporated by reference.

When the inventive stent 10, 30 is compared with the ZILVER (CookMedical) stent, as illustrated in FIGS. 5 and 6, the ZILVER stent has asingle open cell geometry that is uniform throughout the stent. Asillustrated in FIG. 5, the ZILVER stent has a generally WV-shaped opencell geometry, shaded for reference that is consistent along the entirelength of the stent. Moreover, the ZILVER stent has peaks and valleyswith enlarged widths that accommodate connection with the bridge membersrelative to the peaks and valleys that are not connected by bridgemembers. In contrast, the inventive stent 50 has a hybrid open cellgeometry with the first open cells 24 having a generally V-shape and thesecond open cells 28 having a generally Z-shape, both are shaded forreference.

The basic geometry of stent 10, 30 as described above is common to allthe following embodiments, which differ only in i) presence or absencesurface topographical features; ii) presence or absence of a drugcoating; and/or iii) presence or absence of proximal and distalprojections.

Turning to FIGS. 7-10 in the accompanying Figures there is depictedembodiments of the stent 60 having a plurality of volume-enhancingfeatures 62, such as elongate grooves, formed in the outer surface ofthe stent 60. The volume-enhancing features 62 are preferably, but notnecessarily, formed in the entire outer surface of the stent 60,including the rings 16 and the bridge members 18. As an alternative tothe volume-enhancing features 62 being formed in or on the outer surfaceof the stent 60, the volume-enhancing features 62 may be formed in or onan outer surface of a radiopaque coating which is coated onto the outersurface of the stent, as will be described in greater detailhereinafter. Thus, the volume-enhancing features 62 may be formed in theouter surface of the tent 60 or in the outer surface of a radiopaquelayer which, itself, is immediately adjacent the outer surface of thestent 60.

The volume-enhancing features 62 may have virtually any transversecross-sectional shape including, without limitation, V-shape, U-shape,keyhole-shape, or the like. While volume-enhancing features 62 are shownas linear grooves in FIG. 7, the volume-enhancing features 62 may alsobe sinusoidal, meander or have other curvilinear shapes along thelongitudinal axis L of the stent 60. The volume-enhancing features 62each have a width W and a depth D. Depth D and width W may have the samevalue, e.g., 10 μm depth, 10 μm width, or may have different values,e.g., 10 μm depth, 5 μm width. Adjacent grooves 62 further have aninter-groove spacing 64 which is a distance between the adjacent grooves62. The inter-groove spacing 64 may either be measured edge to edge orcenter to center of the adjacent grooves 64. The inter-groove spacing 64may be greater than or equal to the groove 62 width W or, alternatively,may be less than or equal to groove 62 width W. The volume-enhancingfeature 62 may have a width to depth ratio been about 1:1 to about 1:3.The use of the term “groove” intended to be construed as a channel ordepression; a notch or indentation that does not pass entirely throughthe thickness of the material in which the groove is present.

The volume-enhancing features 62 of the present invention are configuredto add between about 20% to about 80% more surface volume to the outeror abluminal surface of the stent. Those skilled in the art willunderstand that the degree of added surface volume is a function of thegeometry, spacing, width and depth of the volume-enhancing features 62on the surface of stent 60.

Vesga, B., et al., demonstrated that the presence of microgrooves on theluminal surfaces of a MULTI-LINK VISION (Abbott Vascular, Santa Clara,Calif.) bare metal coronary stent exhibited significantly lower levelsof neointimal proliferation and greater mature neointima at a fasterrate when compared to flat non-grooved surfaces in humans. Vesga, B., etal. Open Heart 2017; 4: e00052. Doi: 10.1136/openhrt-2016-000521.Methods of forming the microgrooves on the luminal stent surfaces arefound in U.S. Pat. No. 8,512,579, which are hereby incorporated byreference.

Unlike the grooves on the luminal surface of a coronary stent, asdescribed in Vesga, B. et al. or U.S. Pat. No. 8,512,579, the grooves 62of the present invention are present in the outer surface 35 of thestent 60. In accordance with one embodiment of the invention, asillustrated in FIG. 9, stent 60 has a plurality of grooves 62 formed inits outer surface 34 and a drug eluting coating 68 covering the outersurface 34 of the stent 60 and at least partially filling each of theplurality of grooves 62. Regardless of the depth D and width W of thegrooves 62 and regardless of the inter-groove spacing 64, the presenceof the grooves 62 serves to increase the available surface volume forthe drug eluting coating 68 when compared to a non-grooved surface. Itis within the ordinary skill of one in the art through routineexperimentation to determine the desired depth D, width W andinter-groove spacing 64 based upon any given specific stent design.Further, one skilled in the art will understand and appreciate that atthe position of any given groove 62, the thickness of the drug elutingcoating 68 is greater than the thickness of the drug eluting coatingcovering the inter-groove surfaces of the stent 60. The increasethickness of the drug eluting coating 68 in the regions of the grooves62 not only increases the amount of drug capable of eluting from thosegroove 62 regions, but also increases the elution time profile overallwhen compared to non-grooved stent surfaces.

For example, where an individual groove 62 has a width of 10 μm, a depthof 10 μm and a length of 10 mm, for example on an individual bridgemember 18 having a length of 10 mm, the groove 62 provides an additionalvolume of 1.0 mm³. Where there are three grooves 62 on an individualbridge member 18, the total additional volume is 3.0 mm³ when comparedto a non-grooved surface for a single individual bridge member 18.

Where the drug eluting coating 38 has a thickness of about 3-5 μm fromthe outer surface 34 of the stent 60, not including the depth of thegrooves 62, the drug eluting coating 38 will have a thickness of about10 μm when measured from the bottom surface of the grooves 62.

Alternatively, the stent 60 may be provided with grooves 62 and withoutthe drug coating 38 to provide a bare metal grooved stent, with thegrooves 62 on the outer surface 34 of the stent 60.

Turning to FIGS. 11-14 in which the end projections 20 are illustratedin greater detail. End projections 20 extend from an outermost portion57 of peak 40 and serve as a platform for attaching a radiopaque marker.In accordance with an embodiment of the present invention, the endprojections 20 may be a quadrilateral frame defining a central openspace 48. The frame has a first end frame member 44 that is coupled topeak 40 and a second end frame member 44 at an opposing end of the endprojection 20 and in spaced apart relationship to the first end framemember 44. Lateral frame members 46 extend between the first end framemember 44 and the second end frame member 42 and are in spaced apartrelationship with one and other. The central open space 48 is bounded onits lateral aspects by the lateral frame members 46 and on its endaspects by the first end frame member 44 and the second end frame member42. The lateral frame members 46 are preferably thinner in wallthickness than the first end frame member 44 and the second end framemember 42 and are inset from outer lateral edges thereof, therebydefining a first recess 45 and a second recess 43 relative to the outerlateral edges of the first end frame member 44 and the second end framemember 42. Similarly, by having a thinner wall thickness than the firstend frame member 44 and the second end frame member 42, the lateralframe members also define a third recess 47 by this differentialthickness.

A radiopaque cuff member 58 is coupled to the end projection 20. Theradiopaque cuff member 58 may be a tubular member that is flattened orcrimped onto the end projection 20 or it may be a planar member that iswrapped around and secured to the end projection 20. The radiopaque cuffmember 58 seats within and against first recess 45, second recess 43 andthird recess 47 and covers and at least substantially encloses the openspace 48 in the end projection 20. Preferably, the radiopaque cuffmember 58 has a thickness selected to correspond to depths of the firstrecess 45, second recess 43 and third recess 47 such that an outersurface of the radiopaque cuff member 58 lies substantially co-planarwith outer surfaces of the first end frame member 44 and the second endframe member 42.

The outer surfaces of the first end frame member 44 and the second endframe member are preferably co-planar with the outer surface 34 of thestent 10. Similarly, the inner surfaces of the first end frame member 44and the second end frame member are preferably co-planar with the inneror luminal surface of the stent 10. The first end frame member 44, thesecond end frame member 42, and/or the radiopaque cuff 58 may also havegrooves 62 formed in surfaces thereof. Similarly, the first end framemember 44, the second end frame member 42, and/or the radiopaque cuff 58may also have grooves 62 formed in surfaces thereof and may have thedrug eluting coating 68 over the outer surfaces thereof and at leastpartially filling the grooves 62 formed in surfaces thereof.

FIG. 15 depicts a variant of the stent 10, 30 of the present inventionwhich consists of radiopaque coated stent 70. Radiopaque coated stent 70is identical in structure with stent 30, i.e., having sinusoidal rings16 interconnected by bridge members 18, having hybrid open cellstructure with first open cells 24 with a generally V-shape at the firstend 12 and the second end 14 (not shown) and second open cells 28 havinga generally Z-shape along the intermediate section of radiopaque coatedstent 70 and being without end projections 20. Radiopaque stent 70 hasthe addition of a radiopaque coating 72 on the outer surface 34 of theradiopaque coated stent 70. Radiopaque coating 72 is preferably presentonly on low-stress or low-strain regions of the radiopaque coated stent70 and forms a discontinuous partial coating along the longitudinal axisL of the radiopaque coated stent 70. As illustrated in FIG. 15, theradiopaque coating 72 is present only on intermediate sections of thestruts 36 and not present on the struts at the peaks 40, valleys 32 orbridge members 18 of the radiopaque coated stent 70. By forming adiscontinuous partial coating of the radiopaque coating 72 on only thelow-stress or low-strain regions of the radiopaque coated stent 70, riskof delamination of the radiopaque coating 72 from the outer surface 34of the stent 70 during crimping and/or radial expansion of the stent 70is significantly reduced.

Turning now to methods of applying the radiopaque coating 72 to thestent 70, FIGS. 16 and 17 illustrate alternative systems and methods forapplying the radiopaque coating 72. FIG. 16 illustrates the system andmethod 80 for applying the radiopaque coating 72 through a planar mask,whereas FIG. 17 illustrates the system and method 90 for applying theradiopaque coating 72 through a cylindrical mask.

The system and method 80 for applying the radiopaque coating 72 througha planar mask 82 is shown in FIG. 16. Stent 30, 70 is on a mandrel 81.The planar mask 82 has a planar mask window 84 that has a length that isgreater than or equal to the length of the stent 30, 70 and a width thatis less than or equal to the circumferential width of the radiopaquecoating 72 to be applied to the low-stress or low-strain regions of thestent 30, 70. In accordance with the method 80 of the present invention,the radiopaque coating 72 is sputter coated 86 through the planar maskwindow 84 and onto the low-stress or low-strain regions of the stent 30,70. The mandrel 81 is rotated about its longitudinal axis and metered sothat only the low-stress or low-strain regions of the stent 30, 70 areexposed to the planar mask window 84 during each sputter deposition run.The mandrel 81 also protects the inner surface of the stent 30, 70 fromthe radiopaque coating 72 as it is in intimate contact with the innersurface of stent 30, 70. The planar mask 82 is maintained in sufficientproximity to stent 30, 70 during the sputter deposition run so thatthere is no or acceptable levels of overspray of the radiopaque coating72 onto undesired stent regions.

The system and method 90 for applying the radiopaque coating 72 througha cylindrical mask 92 is shown in FIG. 17. Stent 30, 70 is on a mandrel91 and in intimate contact with the mandrel such that the inner orluminal surface of the stent 30, 70 is shielded. The cylindrical mask 92has a plurality of cylindrical mask windows 94, has a length that isgreater than or equal to the length of the stent 30, 70 and a width thatis less than or equal to the circumferential width of the radiopaquecoating 72 to be applied to the low-stress or low-strain regions of thestent 30, 70. In accordance with the method 90 of the present invention,the radiopaque coating 72 is sputter coated 96 through at least one ofthe plurality of cylindrical mask windows 94 and onto the low-stress orlow-strain regions of the stent 30, 70. The mandrel 81 and stent 30, 70may be rotated, or the entire assembly of the mandrel 81, stent 30, 70and cylindrical mask 92 may be rotated about the assembly's longitudinalaxis, or the mandrel 81 and stent 30, 70 may be maintained stationaryand the cylindrical mask 92 rotated about its longitudinal axis and overthe mandrel 81 and stent 30, 70. In any case, the rotation is metered sothat only the low-stress or low-strain regions of the stent 30, 70 areexposed to at least one cylindrical mask window 94 during each sputterdeposition run. Multiple magnetrons having different angularorientations may be employed to accomplish depositing the radiopaquecoating 72 without the need for rotation of the stent 30, 70 during thedeposition run. The cylindrical mask 82 is maintained in sufficientproximity to stent 30, 70 during the sputter deposition run so thatthere is no or acceptable levels of overspray of the radiopaque coating72 onto undesired stent regions. In addition or alternatively, anoverspray mask (not shown) may be employed such that unacceptable levelsof overspray during sputter coating 96 of the radiopaque coating 72 areavoided.

As an alternative to sputter depositing the radiopaque coating, theradiopaque coating may be applied by selective plating or other methods,including, for example, electroplating, brush plating, electrolesschemical plating, or 3D printing.

In accordance with either system and method 80 or system and method 90for depositing the radiopaque coating 72 onto stent 30, 70, theradiopaque coating 72 will have a thickness dependent upon theradiopaque material employed, as different radiopaque materials havediffering degrees of opacity under fluoroscopy. Typically, however, theradiopaque coating 72 will have a thickness between about 2 μm and 10μm.

Where the stent 30, 60, 70 has grooves 62, the grooves 62 may be formedin the outer surface 34 of the stent 30, 60, 70 and then the radiopaquecoating 72 is sputter coated onto the outer surface 34 and into thegrooves 62. Alternatively, the radiopaque coating 72 may be sputtercoated onto the outer surface 34 before the grooves 62 are formed intothe outer surface 34. In this latter case, the grooves 62 will be formedin the radiopaque coating 72 and, depending upon the thickness of theradiopaque coating 72 and the depth of the grooves 62, the grooves 62may pass through the radiopaque coating and into the outer surface 34 ofthe stent 30, 60, 70.

Additionally, in accordance to the embodiment of the invention where adrug coating 68 is employed, the drug-coating 68 will be an outermostlayer covering the radiopaque coating 72 and the grooves 62, if present.

As with all stents, the peripheral stents 10, 30, 60, 70 of the presentinvention require a delivery system to introduce and delivery the stentto a desired in vivo position. FIGS. 18-20B illustrate an embodiment ofa delivery system 100 in accordance with the present invention. As iscommon to stent delivery systems, a retractable sheath 110 covers acatheter 112. Catheter 112 will typically have a guidewire lumen thatpasses either through its entire length in an over-the-wire version orpasses along a more distal portion of the catheter 112 length in arapid-exchange version. A stent mounting region 114 is at a distal endof the catheter 112 and the catheter 114 terminates at its distal endwith an atraumatic tip 116. Retractable sheath 110 is capable ofreciprocal coaxial movement along a portion of the length of thecatheter 112. Sheath 110 will extend to the distal end of the catheter110 and constrain the stent carried on the catheter 112 and typicallyabuts the atraumatic tip 116 in its extended state for delivery. Oncepositioned at a desired situs in vivo the sheath 110 is retractedproximally to expose and deploy the stent.

Handling of the catheter 112 and sheath 110 typically involvesmanipulating some sort of mechanism operably coupled to the catheter 112and sheath 110 and capable of being controlled by an operator. Inaccordance with the delivery system 100 of the present invention, handle102 is provided with a control actuator 104 and a flush port 106 toallow for flushing fluid to be applied through a lumen, such as theguidewire lumen, in the catheter 110.

Handle 102 consists mainly of a housing 120 which contains the controlactuator 104 and into which the catheter 112 or a support tube 132coupled to a proximal end of catheter 112 on its distal end and to aflush luer 143 coupled to the flush port 106 in the housing 120. Thesheath 110 and the catheter 112 or support tube 132 pass through astrain relief member 108 and, optionally, a retaining member 136, bothof which allow the sheath 112 to pass through and into the housing 120.A carrier member 130 is coupled to a proximal end of the sheath 112. Thecarrier member 130 is, in turn, operably coupled to the control actuator104 such that the control actuator 104 applies a motivating force to thecarrier to retract or extend the sheath 112.

In accordance with an embodiment of the delivery system 100 of thepresent invention, the control actuator 104 is a rotary wheel having aunidirectional mechanism 122, such as a one-way bearing or ratchet,mounted on an axle 124 and coupled to the rotary wheel. A hub 138 iscoaxially mounted on the axle 124 and operably coupled to the rotarywheel and/or the one-way bearing 122. An idler pulley 126 is mountedwithin the housing 120 in spaced apart relationship to the controlactuator 104 and a drive member 128, such as a string, belt or wire, iscoupled at one end to the hub 138 and on its opposing end to the carrier130. The drive member 128 is passes over the idler pulley 126 and wrapsaround and unwraps from the hub 138 by actuation of the control actuatoras the carrier reciprocally tracks on the catheter 112 or the supporttube 132. In this manner, the catheter 112 is retained in a fixedposition relative to the handle 102 and the sheath 110 is retracted orextended over the catheter 112 under the influence of the controlactuator 104. FIG. 20A illustrates the extended position of the sheath110 with the carrier 130 in proximal position, whereas FIG. 20Billustrates the retracted position of the sheath with the carrier 13 ina distal position.

The invention claimed is:
 1. A stent having an outer abluminal surfaceand an inner luminal surface, comprising a. A plurality of generallysinusoidal circumferential ring members having peaks and valleys,wherein the plurality of generally sinusoidal circumferential ringmembers is configured to nest with adjacent generally sinusoidalcircumferential ring members when the stent is in a diametricallyunexpanded state; b. A plurality of bridge members interconnectingadjacent pairs of sinusoidal circumferential ring members; c. Aplurality of volume-enhancing features formed in the outer abluminalsurface of the stent in the plurality of generally sinusoidalcircumferential ring members and in the plurality of bridge members,wherein the volume-enhancing features are configured to add betweenabout 20% to about 80% more surface volume to the outer abluminalsurface of the stent as compared to a stent surface without theplurality of volume-enhancing features; and d. A drug eluting layerhaving a thickness of between about 3 μm to about 20 μm from the outerabluminal surface of the stent covering the entire outer abluminalsurface of the stent and fully filling the plurality of volume-enhancingfeatures.
 2. The stent of claim 1, wherein the plurality of generallysinusoidal circumferential ring members further has a substantiallyzig-zag configuration.
 3. The stent of claim 2, further comprising anoffset section intermediate circumferentially adjacent peaks and valleysof each generally sinusoidal circumferential ring member.
 4. The stentof claim 1, wherein the plurality of generally sinusoidalcircumferential ring members and the plurality of bridge members have awall thickness between about 50 μm and about 100 μm.
 5. The stent ofclaim 1, wherein the plurality of volume-enhancing features have a depthbetween about 0.5 μm and about 10 μm.
 6. The stent of claim 5, whereinthe plurality of volume-enhancing features have a spacing of about 2 μmand about 10 μm between adjacent volume-enhancing features.
 7. The stentof claim 5, wherein each of the plurality of volume-enhancing featureshave a width between 0.5 and 10 μm.
 8. The stent of claim 7, whereineach of the plurality of volume-enhancing features have a width to depthratio between about 1:1 and 1:3.
 9. The stent of claim 1, furthercomprising a plurality of projection members extending from a proximaland a distal generally sinusoidal circumferential ring member atproximal and distal ends of the stent.
 10. The stent of claim 9, whereineach of the plurality of projection members further comprises asubstantially quadrilateral frame having a central open region.
 11. Thestent of claim 10, further comprising a radiopaque cuff member joined tothe plurality of projection members.
 12. The stent of claim 11, whereinthe radiopaque cuff member has a portion thereof recessed within thecentral open region.
 13. The stent of claim 1, further comprising aradiopaque coating on at least a portion of the outer abluminal surfaceof the stent.
 14. The stent of claim 1, wherein the plurality ofgenerally sinusoidal circumferential ring members and the plurality ofbridge members further define a plurality of open cells.
 15. The stentof claim 14, wherein the plurality of open cells further comprise atleast two different open cell configurations.
 16. The stent of claim 15,where the at least two different open cell configurations furthercomprise a first open cell configuration positioned at or proximate toopposing ends of the stent and a second open cell configurationpositioned along an intermediate portion of the stent.
 17. The stent ofclaim 16, wherein the first open cell configuration further comprises agenerally V-shaped open cell configuration.
 18. The stent of claim 16,wherein the second open cell configuration further comprises a generallyZ-shaped open cell configuration.
 19. The stent of claim 1, wherein theplurality of volume-enhancing features further comprise a plurality ofelongate grooves.
 20. The stent of claim 19, wherein the plurality ofelongate grooves are oriented substantially parallel to a longitudinalaxis of the stent.